Rheumatoid arthritis (RA) is a common inflammatory disease that affects connective tissue throughout the body. The most common areas affected are the joints. A joint is the location where bones come together. Several structures work together to allow movement of the joint:
- Synovium—A capsule that surrounds and protects the joint. The tissue also produces a fluid that helps lubricate and protect the joint.
- Cartilage—Soft tissue that covers the ends of the bone to allow the bones to glide over each other smoothly.
- Tendons—Strong tissue that connects muscle to bone near the joint. The tendons cross over joints and are critical to allowing movement.
RA is inflammation of the synovium which causes swelling and tenderness in joints. RA symptoms and severity can vary significantly between people. Some may have mild symptoms over a short period of time and some may have more severe forms that lasts many years. RA may also occur in cycles of remission with no symptoms and flare ups where symptoms are more severe.
Over the course of time, inflammation can cause irreversible damage to the cartilage and bone, and weaken nearby tendons which can lead to disability. The earlier RA is detected and treated, the better it can be controlled and damage can be minimized.
Although less common, RA can also affect connective tissue in other areas of the body including:
- The lungs and the lining that surrounds them
- The heart and the lining that surrounds it
- Artery walls
- The whites of the eyes—sclera
RA is an autoimmune disease. The immune system is designed to attack foreign substances in the body, such as viruses or bacteria. With an autoimmune disorder, the immune system mistakenly identifies healthy body tissue as foreign tissue and attacks it. In RA, the joint tissue is attacked. This attack causes irritation and swelling in the synovium and a thickening of the fluid in the joint which causes the hallmark redness, swelling, and stiffness of the joints. Over time, this constant inflammation wears away at the cartilage and bone inside the joint, and makes the nearby tendons weak, making movement painful and difficult.
The exact cause of autoimmune disorders like RA is not known, but is believed to be a combination of:
- Genetic factors—faulty genes may redirect immune system to attack specific healthy tissue
- Environmental factors—may trigger gene defect and/or cause change in immune system
- Chemical or hormonal imbalances in the body
- Reviewer: Michael Woods, MD
- Review Date: 06/2016 -
- Update Date: 05/20/2015 -